1. The Periodic Table

2. Dimitri Mendeleev Father of the Periodic Table
Looked for clues (studied the evidence)
Wrote facts on paper cards
Observed patterns

3. Observations: Melting point Density Color
Atomic mass (as compared to hydrogen)
Bonding power (how many bonds each element formed with oxygen)

4. Copper and Silver are both shinny, tarnish and turn green
Chlorine and Fluorine are both gases and can irritate your lungs

5. Mendeleev’s Observations
Patterns appear when elements are arranged in order of increasing atomic mass
Grouped cards according to patterns
Published first Periodic Table in 1869

6. First Periodic Table

7. The Periodic Table Today
Arranged by atomic number
Over 100 known elements today
Some elements have not been discovered yet – spaces on the Periodic Table have been left for them

8. Groups and Periods 18 vertical columns called GROUPS or FAMILIES
Elements in each group have similar characteristics
Group 1 are the alkali metals – react violently with water
Group 18 are the Noble Gases – rarely react at all
7 horizontal rows called PERIODS
Series of different elements that are not alike
Pattern: reactive to non-reactive

9. What causes bonding power?
Valence electrons
The elements in each group of the periodic table have the same number and arrangement of valence electrons

10. Valence Electrons
Group 1
Alkali Metals
Group 18
Noble Gases